TCP transcription factors are important regulators of plant growth and proliferation processes, such as leaf morphogenesis, petal growth and development, and shoot branching. Here, an RNA-seq analysis revealed that an Acer palmatum class II TCP transcription factor was differentially expressed in 'Jinlinghuangfeng' and the mutant 'Jinlinghuangyu,' which exhibit different expression level of microRNA 319 (miR319). We isolated and functionally characterized this gene, which is named ApTCP2. ApTCP2 expression was detected in the root, stem, and leaf and was strongest in the leaf. ApTCP2 is deposited in the nucleus and exhibits no transcriptional activation ability in yeast. The overexpression of ApTCP2 and ApmTCP2 (an mRNA sequence with synonymous changes from ApTCP2 that exhibits reduced sequence complementarity to miR319) in Arabidopsis jaw-D plants (which overexpress miR319) rescued the leaf defects in these plants. In Arabidopsis, ApTCP2 and ApmTCP2 affected the flowering period, and leaf senescence was accelerated by high expression of ApTCP2 and ApmTCP2. The transcript levels of key jasmonic acid (JA) biosynthesis genes (LIPOXYGENASE [AtLOXs]; AtLOX2, AtLOX3, and AtLOX4) were increased in the transgenic lines. Our results reveal that ApTCP2 plays multiple roles, including modulating leaf morphogenesis, affecting flowering and positively regulating leaf senescence, via miR319, and these effects are at least partially achieved by influencing JA biosynthesis.
